April 23, 2013
01:00 PM (EDT)

News Release Number: STScI-2013-14

Hubble Captures Comet ISON

April 23, 2013: Comet ISON is potentially the "comet of the century" because
around the time the comet makes its closest approach to the Sun,
on November 28, it may briefly become brighter than the full Moon.
Right now the comet is far below naked-eye visibility, and so
Hubble was used to snap the view of the approaching comet, which
is presently hurtling toward the Sun at approximately 47,000
miles per hour. When the Hubble picture was taken on April 10,
the comet was slightly closer than Jupiter's orbit at a distance
of 386 million miles from the Sun. Even at that great distance
the Sun is warming the comet enough to trigger outgassing from
its frozen gases locked up in the solid nucleus. Hubble
photographed a jet blasting dust particles off the sunward-facing
side of the comet's nucleus. Preliminary measurements from the
Hubble images suggest that the nucleus of ISON is no larger than
three or four miles across. The comet was discovered in September
2012 by the Russian-led International Scientific Optical Network
(ISON) using a 16-inch telescope.